A very common reported bug is that this or that unit is not healing as intended, let's hope this clarifies. Basic healing When a unit doesn't move and is injured, it heals: -Inside city: +20 HP -In friendly tile: +15 HP -Outside: +10 HP -In enemy territory: +5 HP If the unit requires a strategic resource from which the player may have run out then the unit does not heal. (Like having Iron: -1, this prevents sword and artillery units from healing and they get a penalty to attack). Naval units cannot heal outside friendly tiles. Fortify until healed action Providing that the units need to not do anything in order to heal, they could fortify while waiting as well, so this action is very handy. Being completely healed is useful against ranged units who can get a bonus against injured units. It's worth noting that the fortify action doesn't work with mounted and armored units as stated. When those units select 'fortify until healed' they actually are 'waiting until healed'. Healing promotions Medic is the most basic stuff for healing. It heals every surrounding unit and itself if conditions for healing are met by an additional +5HP. That means that units that have moved or lack strategic resources won't benefit from being adjacent to a medic unit. March is the other promotion that affects healing. It allows the unit to heal even when the unit has moved. It still won't work on units that demand strategic resources that are missing. Ranged units can get March earlier than melee units. Airplane units can also have a promotion that does the same, but with a different name. Naval units can get a promotion that allows to heal 5 HP when outside friendly territory, but the unit must not do any action that turn. Explorers have their own promotion, Survivalism, that allows them to recover +5 HP when outside friendly territory and grants +25% CS to defence. That's to be added to the basic +10 HP. Other healings Pillaging. Raiding enemy tiles gives money and heals the unit 25 HP. Promoting. Every promotion gives +10HP. Authority. One of the policies heals 20 HP to a melee unit that kills a enemy. Khan. A special Great General that has a medic promotion. Hospital. Heals 15 HP to garrison unit every turn. Pantheon Faith Healers. [Incomplete] Strategies A medic unit ability works on any adjacent friendly unit and itself, and it will work only when all those units are holding or have the march promotion. Being a medic helps the unit to survive a little longer, but it's not very useful to attack with it. By surviving longer, the medic unit helps with flanking bonus and can stand damage on itself while healing. A effective tactic is to pick a high CS melee unit, like a Tercio, and give it Medic and Cover promotions. Then place it in a terrain with defence bonuses and fortify. Units will be safer healing in the rear. March units will heal better in the front. The medic will mostly receive ranged damage, and that's what Cover is for. While it is possible to pick March for the medic unit, it will only be useful in positioning, cause we don't want the medic to attack very often. Being in friendly terrain is as good for our units as it is bad for the enemies. It's a good idea to fight in friendly terrain: You'll recover faster and the enemy will recover slower. Just watch out for pillaging (a mounted unit can pillage, attack and pillage again). Or better yet, spend a Great General to build a fortress. It provides defence to the unit inside the fortress, it damages adjacent enemy units and it steals enemy tiles, so we can heal better and the enemy will heal worse. Those stolen tiles won't have tile improvements being worked by us, and actually they don't use to have many improvements mid-game.